This project attempts to improve detection and diagnosis of breast masses in dense breast tissue by developing an ultrasound imaging system that accurately correlates with x-ray mammography. The Phase I goals were: (1) to develop a manual scanning ultrasound system that allows ultrasound imaging while the breast is compressed by sound-transmitting compression paddles and held in the same positions used in x-ray mammography; (2) to determine the feasibility of automating this system. It was demonstrated that recorded, compressed-breast ultrasound images are of excellent diagnostic quality, and that automated scanning is feasible in the craniocaudal position. The goals of Phase II are to design, build and test an automated three-dimensional ultrasound scanner for compressed- mode imaging, and to assess the clinical utility of this system using both manual and automated scanning. Specific aims of Phase II include: (1) improvement of ultrasound/x-ray transmitting breast compression paddles; (2) refinement of scan automation techniques; (3) automated scanning for mediolateral oblique views; and (4) investigation of techniques for x-ray/ultrasound image registration. Clinical studies will assess the diagnostic advantages of the new techniques over current breast imaging methods. These clinical findings will determine the potential of this 3-D automated x-ray/ ultrasound breast scanner for commercial application. PROPOSED COMMERCIAL APPLICATION: There is a serious need to improve the diagnostic accuracy of x-ray mammography of radiographically dense breasts. The combined x-ray/ultrasound instrument techniques developed in the proposed research can be directly applied to improve current x-ray mammography machines. This combined-instrumentation approach could also be used, without applying the x-ray component, for young subjects or other patients for whom x-ray is not appropriate.